1. Field of the Invention
The present invention relates to a method of fabricating a color filter (CF) substrate, and more particularly, to a method of fabricating a color filter substrate capable of forming a black matrix (BM) and protrusions simultaneously.
2. Description of Related Art
The liquid crystal display (LCD) is one of the most important milestones in the history of displaying techniques. Because the LCD has a light and slim body, consumes very little power and produces very little radiation in operation, it has become one of the mainstream products in the market.
However, the earlier versions of the liquid crystal display suffer from a narrow viewing angle problem. To enhance the viewing angle of the display, the industry has developed a multi-domain vertically aligned (MVA) LCD. The MVA LCD has protrusion structures on the color-filter substrate and/or the active-device-array substrate so that the liquid crystal molecules tilt in multiple directions to enhance the viewing angle of the liquid crystal display.
The process of forming the color-filter substrate of the conventional MVD LCD includes forming a black matrix on a glass substrate. Then, a color filter layer having red, blue and green filter patterns is formed. After that, an overcoat layer and a common electrode are sequentially formed over the foregoing structure. Thereafter, protrusions and photo spacers are separately formed over the common electrode. Finally, an alignment layer is formed over the foregoing structure.
According to the foregoing description, the process of forming the color filter side substrate of the conventional MVD LCD requires at least more than four photo-mask processes. With the current trend of reducing the number of photo-mask processes in the process of forming a liquid crystal display, further simplification of the process is preferred. Therefore, half-tone techniques and back exposure techniques have been developed to reduce the number of photo-masks. However, the half-tone technique is more difficult to implement and the cost of the photo-mask is higher. On the other hand, the back exposure technique has difficulty controlling the width of the black matrix and the level of precision demanded is also high so that there are still plentiful grounds for improvement.